Page 27 - Green Builder's Resilient Housing Design Guide 2019

Best Practices for a

Storm-Ready ICF Structure

1. Hire a qualified installer. The installer on your project
should be trained and certified in the particular ICF
system specified. Some product manufacturers offer
site visits at several points throughout the install.
2. Stick to ICFs for exterior envelope. For best storm
resilience, avoid transitions to other framing systems
such as wood framing on the building exterior. ICF
walls perform best when designed and reinforced
consistently.
3. Avoid inefficient wall sizes/shapes. Walls with bump-ins
or bump-outs result in shorter walls (i.e., less useful
living spaces) or shifting of windows. Whenever
possible, straighten bump-ins and bump-outs. This
will not only add construction efficiency and living
space, but reduce the need for more costly corner/
specialty blocks.
4. Be aware of the right attachments. When securing
items (such as floor ledger boards, brick ties, bracing,
etc.) to the ICF, use the method recommended by the
ICF supplier.
5. Work efficiently with wall lengths. A strategy for
combining multiple ICF blocks and working with
cuts/seams will have a major impact on project speed
and quality. Select even-inch increments for wall Smaller Vibes. Using a narrow concrete vibrator ensures good wall fill, and reduces risk
lengths whenever possible, because the connection of form blowouts.
pattern repeats every inch, thereby making stacking far easier. 8. Don’t compromise the thermal envelope. Maintain continuity of
Work with the block’s web spacing increments to ensure that insulation, and avoid cantilevered concrete floors or exposed slab
all embedded attachment points are vertically aligned, allowing edges to prevent thermal breaks. Insulate broken or damaged
for smooth application of finishes. Do not take pains to achieve areas in the foam panels. Proper detailing of door and window
zero cuts in an ICF block—use of a seam (offset joint or standing jambs can help maintain the thermal performance of the building
seam) often eliminates layout problems, speeds up the process, envelope.
and ensures that the majority of plastic webs are aligned. 9. Avoid heavy vibrating during concrete pour. ICF walls should be
6. Brace ICF forms from the inside. Proper bracing is the key to vibrated to remove voids in the concrete. Consider using a small-
ensuring that walls are straight and plumb, which is critical to diameter mechanical vibrator, to allow concrete to spread evenly
structural integrity and also to streamline subcontract finishing and maintain integrity.
work. The higher the wall, the harder it is to reach the exterior 10. Make sure the concrete completely fills the form. To avoid holes
with bracing, so brace from the inside. Rather than creating your and gaps in the concrete pour, be familiar with the structural
own bracing system, go with the ICF manufacturer-recommended requirements and the design of the webs. It is highly
(OSHA approved) scaffolding/ bracing system that works best recommended for the structural engineer to know the specific
with their products. ICF block, thus optimizing the placement of rebar in webs.
7. Strategically place a vertical or stack joint. In applications where 11. Choose the proper mechanical system. Because ICF is so energy-
a vertical or stack joint is required, place the joint over a door efficient, mechanical engineers need to factor this in as they
or window opening to minimize the required length of the joint calculate HVAC requirements. In fact, if an HVAC unit is
and associated labor. Be sure to properly brace and strap the joint oversized, it can actually create humidity/moisture issues in the
at this critical juncture. Importantly, Maintain proper horizontal interior. Also, plan for “after the storm” drying scenarios. What
dimensions above and below openings. will work best, given the building’s size and layout? GB

www.greenbuildermedia.com Resilient Housing Design Guide GREEN BUILDER MEDIA 27